4 NORTH AMERICAN FAUNA 76 



Study Area 



Our 21,000 km2 study area includes the mountainous region that 

 forms the spine terminating in the peninsula that separates Kuskokwim 

 Bay and Bristol Bay, and the adjoining lowlands and coastal waters. This 

 area comprises portions of the three biogeographic regions delineated 

 by Kessel and Gibson (1978) as southwestern, western, and central. The 

 eastern boundary of our study area followed the eastern foothills of the 

 Togiak River valley from Kulukak Bay northwards to Togiak Lake and 

 other source lakes (Fig. 1). It then followed the east-west divide of the 

 Kilbuck Mountains to the Salmon River and down the Salmon River to its 

 confluence with the Aniak River. The northern boundary from the Aniak 

 River west to Ophir Creek was an imaginary line about 75 m asl along the 

 indefinite limit of the foothills above the lower Kuskokwim plain. The 

 western boundary ran south from Ophir Creek along the sharply defined 

 outer limit of the foothills to the coast at Jacksmith Bay. From there, the 

 boundary ran southwest to Cape Newenham and then east to just west 

 of Kulukak Bay. The study area included Jacksmith Bay, Carter Bay, 

 Goodnews Bay, Chagvan Bay, Security Cove, Nanvak Bay, Togiak Bay, all 

 waters within 5 km of the coast, and all nearby islands, including Hage- 

 meister Island, Summit Island, and the Walrus Islands. 



The area is geologically complex (Hoare and Coonrad 1959, 1961; 

 Selkregg 1976). In general, it is underlain by mesozoic sedimentary and 

 metamorphic rocks, with some areas of volcanic and intrusive rocks. 

 Nearly all of the area was glaciated in the Pleistocene, except perhaps 

 the lower valleys of the rivers flowing from the Kilbuck Mountains 

 (Hartmann and Johnson 1977). Some of the area is underlain by continual 

 permafrost (Hartmann and Johnson 1977). 



The climate of the study area is transitional and continental in the 

 northern portion, transitional over the remaining inland areas, and mari- 

 time at capes and offshore islands (Hartmann and Johnson 1977). Tem- 

 peratures 175 km inland at Nyac range from -45° C in winter (mean high 

 and low, -1 1° C and -20° C, respectively) to 30° C in summer (mean high 

 and low, 19° C and 3° C, respectively; Hartmann and Johnson 1977). On 

 the coast, temperatures range from -33° C in winter (mean high and low, 

 -7° C and -l6° Q to 24° C in summer (mean high and low of 15° C and 

 7° C; Brower et al. 1988). The entire area receives about 100 cm of 

 precipitation each year, including about 200 cm of snow. Inland, ice 

 forms on rivers beginning in October, and rivers are usually ice-free in 

 early May. Along the west coast, fast or close ice forms beginning in 

 October and may last until May, and ice may extend to several kilometers 

 south of the study area in some years (Brower et al. 1988). 



